JPS6150118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor and a radiation intensifying screen (hereinafter abbreviated as "intensifying screen") using this phosphor. More specifically, the present invention provides a fluorohalide phosphor activated with divalent europium (Eu ²⁺ ) and an intensifying screen having a phosphor film made of the Eu ²⁺ -activated fluorohalide phosphor. Regarding.

As Eu ²⁺ activated fluorohalide phosphor,
The composition formula is (Ba _1-y , M〓 _y )FX: aEu ²⁺ (where M〓 is at least one of Mg, Ca, Sr, Zn, and Cd, and X is at least one of Cl, Br, and I). 1, and y and a are each 0
Eu ²⁺ -activated fluorohalide phosphors are known which satisfy the following conditions: ≦y≦0.7 and 0<a≦5×10 ⁻² . This phosphor emits near-ultraviolet to blue light with a peak around 390 nm when excited by X-rays, ultraviolet rays, and electron beams, and is particularly useful as a phosphor for intensifying screens because it has a high absorption efficiency for X-rays. It is something. However, when taking radiographs for the purpose of medical diagnosis, for example, it is necessary to reduce the exposure dose of the subject (patient) as much as possible, so an intensifying screen with even higher sensitivity is desired. Therefore, as a phosphor for an intensifying screen, a phosphor having higher luminous efficiency than the Eu ²⁺ -activated fluorohalide phosphor is desired.

The present invention uses Eu ²⁺ activated fluorohalide fluorophores that emit light with higher efficiency than the conventional Eu ²⁺ activated fluorohalide phosphors when excited by X-rays, ultraviolet rays, electron beams, etc. The purpose is to provide the body.

Furthermore, the present invention provides Eu ²⁺ with improved luminous efficiency.
The object of the present invention is to provide a highly sensitive intensifying screen using an activated fluorohalide phosphor.

In order to achieve the above object, the present inventors conducted various studies and repeated experiments on conventional Eu ²⁺ -activated fluorohalide phosphors. As a result, we discovered that replacing barium (Ba), one of the base components of this phosphor, with an appropriate amount of beryllium (Be) improves the luminous efficiency under X-ray, ultraviolet, and electron beam excitation. The invention was completed.

The Eu ²⁺ -activated fluorohalide phosphor of the present invention has a composition formula (Ba _1-xy , Be _x , M〓 _y )FX: aEu ²⁺ (where M〓 is Mg, Ca, Sr, Zn). and Cd, X is at least one of Cl, Br and I, and x, y and a are 0<x
≦0.5, 0≦y≦0.7, x+y<1 and 0<a≦
It is a number that satisfies the condition of 5 × 10 ^-2 ). Particularly from the viewpoint of luminous efficiency, the more preferable x and a value ranges in the above compositional formula are 0.1≦x≦0.35 and 10 ⁻⁵ ≦a≦10 ⁻² , respectively.

Further, the intensifying screen of the present invention is characterized in that it has a fluorescent film made of the Eu ²⁺ -activated fluorohalide phosphor of the present invention.

The Eu ²⁺ activated fluorohalide phosphor of the present invention is produced by the production method described below. First, as raw materials for the phosphor, (1) one or more divalent metal fluorides consisting of BaF ₂ , BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , ZnF ₂ and CdF ₂ (2) Ba, Be , one or more divalent metal halides consisting of chlorides, bromides and iodides of Mg, Ca, Sr, Zn and Cd, or
One or more ammonium halides consisting of NH ₄ Cl, NH ₄ Br, and NH ₄ I, or one or more of the above divalent metal halides and one or more of the above ammonium halides. , and (3) EuF ₃ , EuCl ₃ , EuBr ₃ , Eu ₂ O ₃ , Eu(NO ₃ ) ₃
One or more europium compounds such as these are used. The above three phosphor raw materials are stoichiometrically (Ba _1-xy , Be _x , M〓 _y )FX・aEu ³⁺ (where M〓 is at least one of Mg, Ca, Sr, Zn, and Cd). , X is at least one of Cl, Br and I, and x, y and a are 0<x
≦0.5, 0≦y≦0.7, x+y<1 and 0<a≦
This is a number that satisfies the condition of 5×10 ^-2 . The same applies below. ) Weigh the ingredients so that the composition formula becomes as follows, and mix thoroughly using a ball mill, mixer mill, etc. From the viewpoint of luminous efficiency of the obtained phosphor, the more preferable ranges of the x and a values of the above mixed composition formula are each 0.1.
≦x≦0.35 and 10 ⁻⁵ ≦a≦10 ⁻² . As is clear from the above-mentioned compositional formula of the phosphor, Ba and Be are among the metals contained in the matrix of the phosphor of the present invention.
is mandatory. Therefore, one type of divalent metal fluoride in (1) above and one type of divalent metal halide in (2) are used for (Ba _1-x , Be _x )FX: aEu ²⁺ fluorescence. In this case, the combination of (1) and (2) is limited to the production of halides of BaF ₂ and Be and BeF ₂ and
Needless to say, it is one of the halides of Ba. In addition, if ammonium halide is used as (2) and no divalent metal halide is used, two or more types of divalent metal fluorides in (1) must be used, and in this case BaF ₂ and BeF ₂
must be used. The ammonium halide in (2) above is used to supply halogen (X), which is one of the base components of the phosphor of the present invention, and ammonium ions (NH ₄ ⁺ ) are Addition of ammonium results in a stoichiometric excess of F (included in (1) above) or other halogens (if divalent metal halides are used together with ammonium halide as (2)), It will be dissipated during firing along with the phosphor, and will not remain in the phosphor. Further, an equimolar amount of an aqueous solution of alkali metal fluoride such as NaF or KF was added in advance to the aqueous solution of the divalent metal halide in (2) above to form a precipitate of the divalent metal fluorohalide. The divalent metal fluorohalide and the above (1) to (3) may be mixed stoichiometrically (Ba _1-xy , Be _x , M _y )FX: aEu ³⁺ . The reaction formula for precipitation of the divalent metal fluorohalide is expressed as follows when, for example, BaCl ₂ is used as the divalent metal halide and NaF is used as the alkali metal fluoride.

BaCl ₂ +NaF→BaFCl↓+NaCl Next, the above phosphor raw material mixture was poured into an alumina crucible.
It is filled into a heat-resistant container such as a quartz crucible or a quartz boat and fired. The firing is performed in a reducing atmosphere such as a nitrogen gas atmosphere containing 2% hydrogen or a carbon atmosphere, in order to convert Eu ³⁺ to Eu ²⁺ . A suitable firing temperature is 600°C to 1000°C. More preferably it is 700°C to 950°C. The firing time varies depending on the filling amount of the phosphor raw material mixture, firing temperature, etc.
In the above firing temperature range, 1 to 10 hours is appropriate. Note that once the phosphor raw material mixture has been fired under the above firing conditions to produce a phosphor, it can be re-fired once or twice or more under the same firing conditions as above to produce a phosphor with better luminous efficiency. You can get a body.

After firing, a phosphor is obtained by performing various operations generally employed in the production of phosphors, such as washing, drying, and sieving. Note that the Eu ²⁺ activated fluorohalide phosphor of the present invention easily decomposes in hot water, so wash it with cold water (below 15°C), acetone,
This is carried out using an organic solvent such as ethyl acetate, butyl acetate, or ethyl alcohol.

The present invention obtained by the manufacturing method described above
Eu ²⁺ activated fluorohalide phosphor contains no conventional Be under X-ray, UV and electron beam excitation
It exhibits near-ultraviolet to blue light emission with higher efficiency than Eu ²⁺ -activated fluorohalide phosphors.

Figure 1 shows the emission spectrum and excitation spectrum of Ba _{0.8 Be 0.2 FBr} :0.001Eu ²⁺ phosphor _, which is one of the Eu ²⁺ -activated fluorohalide phosphors of the present invention. Curve a is the emission spectrum when excited with 253.7 nm ultraviolet light, and curve b is the excitation spectrum. As is clear from curve a in FIG. 1, the Eu ²⁺ -activated fluorohalide phosphor of the present invention emits near ultraviolet to blue light having an emission peak around 390 nm. The emission spectrum of the Eu ²⁺ -activated fluorohalide phosphor of the present invention, shown by this curve a, is almost the same as the emission spectrum of the conventional Eu ²⁺ -activated fluorohalide phosphor that does not contain Be. It is. Curve a in Figure 1 is the emission spectrum when the Ba _0.8 Be _0.2 FBr:0.001Eu ₂₊ phosphor is excited with ultraviolet light, but it is also _the emission spectrum when excited with X-rays or electron beams, ^or when the fluorescent material is excited with Even if the composition of the body changes within the range of the above composition formula, the emission spectrum will hardly change.
It was confirmed that it exhibited near-ultraviolet to blue light emission with an emission peak around 390 nm.

Figure 2 shows one of the Eu ²⁺ activated fluorohalide phosphors of the present invention (Ba _{0.9 -x} , _Bex , Ca _0.1 ) _.
This is a graph showing the relationship between the Be amount x value and the luminance when an FBr:0.005Eu ²⁺ phosphor is excited with X-rays at a tube voltage of 120 KVp. As is clear from Figure 2,
(Ba ₀ . _9-x , Be _x , Ca ₀ . ₁ ) FBr: _0.005Eu ²⁺ phosphor has _the conventional (Ba _{0 .} ) FBr: Shows higher luminance than 0.005Eu ²⁺ phosphor. Especially when the x value is 0.1 within the above range
When the range is ≦x≦0.35, the luminance is extremely high. Figure 2 is a graph showing the relationship between the x value and luminance when excited by X-rays, but the relationship between the x value and luminance when excited by ultraviolet rays or electron beams is similar to that in Figure 2. It was the same. Figure 2 shows data for the (Ba _{0.9 -x} , _Bex , Ca _0.1 ) FBr:0.005Eu ²⁺ phosphor, but the M〓, X, y values, and a values are the same as _above . It was confirmed that for other phosphors of the present invention having different values, the relationship between the x value and the emission brightness had the same tendency as shown in FIG. As described above, the luminance of the Eu ²⁺ -activated fluorohalide phosphor of the present invention varies greatly depending on the Be amount x value.
The emission brightness also changes depending on the Eu ²⁺ activation amount a value, and the emission brightness is particularly high when the a value is in the range of 10 ^-5 ≦a≦10 ^-2 .

As described above, the Eu ²⁺ -activated fluorohalide phosphor of the present invention has higher efficiency than the conventional Eu ²⁺ -activated fluorohalide phosphor under X-ray, ultraviolet, and electron beam excitation. It shows the luminescence of. Especially Eu ²⁺ of the present invention
The activated fluorohalide phosphor has a high X-ray absorption efficiency similar to the conventional Eu ²⁺ activated fluorohalide phosphor, and its emission spectrum is similar to that of regular-type X-ray photographic film. Since it matches the sensitivity, it is useful as a phosphor for intensifying screens. The intensifying screen using the Eu ²⁺ -activated fluorohalide phosphor of the present invention will be described below.

An intensifying screen basically consists of a support such as paper or plastic and a phosphor layer (fluorescent film) provided on one side of the support. The phosphor layer has a phosphor dispersed in a binder resin, and the surface of the phosphor layer (the surface opposite to the support side) is generally protected by a transparent protective film such as a polyethylene terephthalate film. In addition, some intensifying screens have a light-reflecting layer or a light-absorbing layer between the support and the phosphor layer. Some intensifying screens used have a metal foil interposed between the support and the phosphor layer. The structure of the intensifying screen of the present invention is the same as that of the conventional intensifying screen. That is, the intensifying screen of the present invention essentially includes a support made of paper, plastic, etc., and the Eu ²⁺ of the present invention provided on this support.
It consists of a phosphor layer in which an activated fluorohalide phosphor is dispersed in a binder resin such as nitrified cotton. The phosphor layer is prepared by conventional methods. That is, a suitable amount of the Eu ²⁺ -activated fluorohalide phosphor of the present invention and a binder resin such as nitrified cotton are mixed, and an appropriate amount of a solvent is added thereto to prepare a phosphor coating liquid with an optimum viscosity. This phosphor coating solution is then coated onto a support using a roll coater, knife coater, etc. and dried to form a phosphor layer. In addition, in the case of an intensifying screen having a structure having a light reflection layer, a light absorption layer, or a metal foil between the support and the phosphor layer, the light reflection layer, light absorption layer, Alternatively, a phosphor coating solution is applied onto metal foil and dried to form a phosphor layer. A dispersant to improve the dispersibility of the phosphor when creating the phosphor layer, or a plasticizer such as dibutyl phthalate or methyl phthalyl ethylene glycol to increase the flexibility of the resulting intensifying screen. Additives such as the following may be added to the phosphor coating solution. In the intensifying screen of the present invention, the coating weight of the phosphor is suitably 20 to 200 mg/cm ² , more preferably 30 to 150 mg/cm ² . Generally, many intensifying screens have a transparent protective film on the phosphor layer to protect the phosphor layer, but it is preferable to provide a transparent protective film in the intensifying screen of the present invention as well. This is mainly to protect the phosphor layer from moisture, and it is desirable to form the transparent protective film from a non-porous resin such as polyvinyl chloride, polyethylene, or acrylic resin.

The excellent luminescent properties of the Eu ²⁺ -activated fluorohalide phosphor of the present invention under X-ray excitation are maintained in the intensifying screen of the present invention using this phosphor. That is, when comparing intensifying screens manufactured under the same conditions, the intensifying screen of the present invention has higher sensitivity than the conventional intensifying screen using an Eu ²⁺ activated fluorohalide phosphor that does not contain Be. It is.

The intensifying screen of the present invention using the Eu ²⁺ -activated fluorohalide phosphor of the present invention has been described above, but the Eu ²⁺ -activated fluorohalide phosphor of the present invention can be Since it shows highly efficient light emission under X-ray excitation as well as under X-ray excitation, it can also be used as a fluorescent film for discharge lamps, cathode ray tubes, etc.

As explained above, the present invention provides an Eu ²⁺ -activated fluorohalide phosphor that emits light with high efficiency under X-ray, ultraviolet ray, and electron beam excitation, and this Eu ²⁺ -activated fluorohalide phosphor. The present invention provides an intensifying screen using a body, and the industrial utility value of the present invention is extremely large.

Next, the present invention will be explained with reference to Examples.

Example 1 Barium fluoride (BaF ₂ ) 140.3 g (0.8 mol) Barium bromide (BaBr ₂ 2H ₂ O)
266.5 g (0.8 mol) Beryllium fluoride (BeF ₂ ) 9.4 g (0.2 mol) Beryllium bromide (BeBr ₂ ) 33.8 g (0.2 mol) Europium oxide (Eu ₂ O ₃ ) 0.36 g (0.001 mol) Each of the above fluorescence The raw materials were thoroughly mixed using a ball mill. The resulting mixture was filled into a quartz crucible, placed in an electric furnace, and heated in a nitrogen atmosphere containing 2% hydrogen.
It was baked at a temperature of 850°C for 2 hours. After firing, the fired product was cooled and passed through a sieve to make the particle size uniform. In this way, ^{a Ba 0.8 Be 0.2 FBr:0.001Eu 2+} _{phosphor was obtained .} When excited with X-rays at a tube voltage of 120 KVp, this phosphor exhibited an emission brightness that was 190% of that of the Be-free BaFBr:0.001Eu ²⁺ phosphor. Also
Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 2 Barium fluoride (BaF ₂ ) 122.7 g (0.7 mol) Beryllium fluoride (BeF ₂ ) 9.4 g (0.2 mol) Calcium fluoride (CaF ₂ ) 7.8 g (0.1 mol) Ammonium bromide (NH ₄ Br)
97.9 g (1.0 mol) Europium oxide (Eu ₂ O ₃ ) 0.88 g (0.0025 mol) The above-mentioned phosphor raw materials were thoroughly mixed using a ball mill. The resulting mixture was filled into a quartz crucible, placed in an electric furnace, and heated at a temperature of 800°C for 3 hours in a carbon atmosphere.
Baked for an hour. After firing, the fired product was cooled and passed through a sieve to make the particle size uniform. In this way _, a (Ba _{0.7 Be 0.2 Ca 0.1} ) FBr:0.005Eu ²⁺ phosphor was obtained. _{This phosphor does not contain Be (Ba 0.9 Ca 0.1} ) FBr when excited with X-rays at a tube voltage _of 120 KVp:
The luminance was 265% of that of the 0.005Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 3 Equivalent amounts of barium chloride (BaCl ₂ 2H ₂ O) and sodium fluoride (NaF) were each dissolved in water to form BaCl ₂
Aqueous solutions and NaF aqueous solutions were prepared. Next, both aqueous solutions were mixed little by little with stirring. The resulting precipitate was filtered and dried. BaFCl was thus obtained. In addition to 172.6 g (0.9 mol) of BaFCl, the following materials were used as phosphor raw materials.

Beryllium fluoride (BeF ₂ ) 4.2 g (0.09 mol) Magnesium fluoride (MgF ₂ ) 0.6 g (0.01 mol) Ammonium chloride (NH ₄ Cl)
5.3 g (0.1 mol) Europium oxide (Eu ₂ O ₃ ) 0.18 g (0.0005 mol) The above-mentioned phosphor raw materials were thoroughly mixed using a ball mill. The resulting mixture was filled into a quartz crucible, placed in an electric furnace, and heated at a temperature of 850°C in a carbon atmosphere for 3 hours.
Baked for an hour. After firing, the fired product was cooled and passed through a sieve to make the particle size uniform. In this way, a (Ba ₀ . ₉ Be ₀ . ₀₉ Mg ₀ . ₀₁ ) FCl: 0.001Eu ²⁺ phosphor was obtained. When excited with X-rays at a tube voltage _of 120 KVp, _{this phosphor contains no Be (Ba 0.99 Mg 0.01} ) FCl:
The luminance was 253% of that of the 0.001Eu ²⁺ phosphor. Furthermore, when excited with a 253.7 nm ultraviolet electron beam, similar high-intensity light emission was exhibited.

Example 4 Barium fluoride (BaF ₂ ) 140.3 g (0.8 mol) Beryllium fluoride (BeF ₂ ) 4.7 g (0.1 mol) Strontium fluoride (SrF ₂ )
12.6 g (0.1 mol) Ammonium Bromide (NH ₄ Br)
97.9 g (1.0 mol) Europium oxide (Eu ₂ O ₃ ) 0.18 g (0.0005 mol) The above-mentioned phosphor raw materials were thoroughly mixed using a ball mill. The resulting mixture was filled into a quartz crucible, placed in an electric furnace, and heated in a nitrogen atmosphere containing 2% hydrogen.
It was baked at a temperature of 800°C for 3 hours. After firing, the fired product was cooled and passed through a sieve to make the particle size uniform. In this way, a (Ba ₀ . ₈ Be ₀ . ₁ Sr ₀ . ₁ ) FBr: 0.001Eu ²⁺ phosphor was obtained. _{This phosphor does not contain Be (Ba 0.9 Sr 0.1} ) FBr when excited by X-rays with a tube voltage _of 120 KVp:
The luminance was 200% of that of 0.001Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 5 Barium fluoride (BaF ₂ ) 140.3 g (0.8 mol) Beryllium fluoride (BeF ₂ ) 4.7 g (0.1 mol) Magnesium fluoride (MgF ₂ ) 6.2 g (0.1 mol) Ammonium fluoride (NH ₄ Br)
97.9 g (1 mol) Europium oxide (Eu ₂ O ₃ ) 0.88 g (0.0025 mol) The same procedure as in Example 2 was carried out except that the above-mentioned phosphor raw materials were used (Ba ₀ . ₈ Be ₀ . ₁ Mg ₀ . ₁ ) FBr: 0.005Eu ²⁺ fluorophore was obtained. _This phosphor does not contain Be (Ba _0.9 Mg _0.1 ) FBr when excited with X-rays at a tube voltage _of 120 KVp:
The luminance was 215% of that of the 0.005Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 6 Barium fluoride (BaF ₂ ) 140.3 g (0.8 mol) Beryllium fluoride (BeF ₂ ) 4.7 g (0.1 mol) Strontium fluoride (SrF ₂ )
12.6 g (0.1 mol) Ammonium Bromide (NH ₄ Br)
97.9 g (1 mol) Europium fluoride (EuF ₃ ) 0.84 g (0.004 mol) Same as Example 2 except that each of the above phosphor raw materials was used (Ba ₀ . ₈ Be ₀ . ₁ Sr ₀ . ₁ ) FBr: 0.004Eu ²⁺ fluorophore was obtained. _{This phosphor does not contain Be (Ba 0.9 Sr 0.1} ) FBr when excited by X-rays with a tube voltage _of 120 KVp:
The luminance was 236% of that of the 0.004Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 7 Barium fluoride (BaF ₂ ) 157.8 g (0.9 mol) Beryllium fluoride (BeF ₂ ) 3.8 g (0.08 mol) Zinc fluoride (ZnF ₂ ) 2.1 g (0.02 mol) Ammonium chloride (NH ₄ Cl)
50.5 g (1 mol) Europium fluoride (EuF ₃ ) 1.04 g (0.005 mol) The same procedure as in Example 1 was carried out except that each of the above phosphor raw materials was used (Ba ₀ . ₉ Be ₀ . ₀₈ Zn ₀ . ₀₂ ) FCl:0.005Eu ²⁺ fluorophore was obtained. This phosphor does not contain Be (Ba ₀ . ₉₈ Zn ₀ . ₀₂ ) when excited by X-rays with a tube voltage of 120 KVp.
The luminance was 216% of that of FCl:0.005Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 8 Barium fluoride (BaF ₂ ) 70.1 g (0.4 mol) Barium chloride (BaCl ₂ 2H ₂ O)
97.7 g (0.4 mol) Beryllium fluoride (BeF ₂ ) 7.05 g (0.15 mol) Cadmium chloride (CdCl ₂ 2.5H ₂ O)
11.4 g (0.05 mol) Europium oxide (Eu ₂ O ₃ ) 0.18 g (0.0005 mol) The same procedure as in Example 4 was carried out except that the above phosphor raw materials were used (Ba ₀ . ₈ Be ₀ . ₁₅ Cd ₀ . ₀₅ ) FCl: 0.001Eu ²⁺ fluorophore was obtained. This phosphor does not contain Be (Ba ₀ . ₉₅ Cd ₀ . ₀₅ ) when excited by X-rays with a tube voltage of 120 KVp.
The luminance was 190% of that of FCl:0.001Eu ²⁺ phosphor. Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 9 Barium fluoride (BaF ₂ ) 140.3 g (0.8 mol) Beryllium fluoride (BeF ₂ ) 4.7 g (0.1 mol) Strontium fluoride (SrF ₂ )
12.6 g (0.1 mol) Ammonium iodide (NH ₄ I) 29.0 g (0.2 mol) Ammonium bromide (NH ₄ Br)
78.4 g (0.8 mol) Europium fluoride (EuF ₃ ) 0.21 g (0.001 mol) The same procedure as in Example 2 was carried out except that the above phosphor raw materials were used (Ba ₀ . ₈ Be ₀ . ₁ Sr ₀ . ₁ ) _FBr0.8I0.2 ^: _{0.001Eu2 + _}
I got a phosphor. This phosphor has a tube voltage of 120KVp
When excited by a line, it does not contain Be (Ba ₀ . ₉ Sr ₀ . ₁ )
FBr _{0.8 I 0.2 :} 180% _of the luminance of 0.001Eu ²⁺ phosphor
It showed a luminance of . Furthermore, when excited with a 253.7 nm ultraviolet electron beam, similar high-intensity light emission was exhibited.

Example 10 Barium fluoride (BaF ₂ ) 122.7 g (0.7 mol) Beryllium fluoride (BeF ₂ ) 9.4 g (0.2 mol) Calcium fluoride (CaF ₂ ) 7.8 g (0.1 mol) Ammonium bromide (NH ₄ Br)
49 g (0.5 mol) Ammonium iodide (NH ₄ I)
72.5 g (0.5 mol) Europium oxide (Eu ₂ O ₃ ) 0.54 g (0.0015 mol) The same procedure as in Example 2 was carried out except that each of the above phosphor raw materials was used (Ba ₀ . ₇ Be ₀ . ₂ Ca ₀ . ₁ ) _{FBr 0.5} Cl _{0.5 :}
0.003Eu ²⁺ fluorophore was obtained. This phosphor has a tube voltage
When excited with 120 KVp X-rays, it exhibited a luminance that was 205% of that of Be-free (Ba ₀ . ₉ Ca ₀ . ₁ ) FBr _0.5 Cl _{0 .5} :0.003Eu ²⁺ phosphor. Also
Similar high-intensity light emission was also observed when excited with 253.7 nm ultraviolet rays and electron beams.

Example 11 Using each of the Eu ²⁺ activated fluorohalide phosphors of the present invention of Examples 1 to 10, intensifying screens were prepared by the method described below.

First, 8 parts by weight of the phosphor and 1 part by weight of nitrified cotton were mixed in a solvent (acetone, ethyl acetate, and butyl acetate in 1 part).
(mixed at a weight ratio of 1:8) to prepare a phosphor coating liquid with a viscosity of 50 centistokes. Next, use a knife coater to uniformly apply this phosphor coating solution onto a polyethylene terephthalate support having a carbon black light absorption layer approximately 0.25 mm thick so that the phosphor coating weight is approximately 50 mg/cm ² . and dried at 50°C to form a phosphor layer. Further, an acrylic resin was uniformly applied onto this phosphor layer and dried to form a transparent protective film with a thickness of approximately 10 μm.

Each intensifying screen of the present invention thus obtained does not contain Be as described in each example when used in combination with a regular type X-ray photographic film.
It showed higher photographic sensitivity than an intensifying screen made using the same method as above using Eu ²⁺ -activated fluorohalide phosphor. The photographic sensitivity of each intensifying screen of the present invention compared with each intensifying screen using an Eu ²⁺ activated fluorohalide phosphor that does not contain Be is the same as that of the present invention described in each example. The luminance almost corresponded to the luminance of each phosphor.

[Brief explanation of the drawing]

FIG. 1 shows the emission spectrum (curve a) and excitation spectrum (curve b) of the Eu ²⁺ -activated fluorohalide phosphor of the present invention. Figure 2 shows the present invention.
2 is a graph showing the relationship between Be amount x value and luminance in an Eu ²⁺ activated fluorohalide phosphor.

Claims (1)

[Claims] 1. The compositional formula is (Ba _1-xy , Be _x , M〓 _y )FX: aEu ²⁺ (where M〓 is at least one of Mg, Ca, Sr, Zn and Cd, is at least one of Cl, Br and I, and x, y and a are 0<x
≦0.5, 0≦y≦0.7, x+y<1 and 0<a≦
A ^divalent europium-activated fluoride halide phosphor represented by: 2. The phosphor according to claim 1, wherein x and a are numbers satisfying the following conditions, respectively: 0.1≦x≦0.35 and 10 ^-5 ≦a≦10 ^-2 . 3 The compositional formula is (Ba _1-xy , Be _x , M〓 _y )FX: aEu ²⁺ (where M〓 is at least one of Mg, Ca, Sr, Zn, and Cd, and X is Cl, Br, and I at least one of x, y and a are 0<x
≦0.5, 0≦y≦0.7, x+y<1 and 0<a≦
A radiation intensifying screen characterized by having a phosphor film made of a divalent europium-activated fluorohalide phosphor represented by: 5×10 ^-2 . 4. The radiation intensifying screen according to claim 3, wherein x and a are numbers satisfying the following conditions, respectively: 0.1≦x≦0.35 and 10 ⁻⁵ ≦a≦10 ⁻² .